Stacked Transparent Pixel Structures for Image Sensors

ABSTRACT

In one embodiment, a pixel for an image sensor includes a first subpixel and a second subpixel stacked on top of the first subpixel. Each of the first and second subpixels include a polygon shape. Each of the first and second subpixels include a photodetector layer, a transparent cathode layer, and a transparent anode layer.

TECHNICAL FIELD

This disclosure relates generally to pixels and more particularly tostacked transparent pixel structures for image sensors.

BACKGROUND

Pixels are utilized in a variety of electronic displays and sensors. Forexample, displays used in smartphones, laptop computers, and televisionsutilize arrays of pixels to display images. As another example, sensorsused in cameras utilize arrays of pixels to capture images. Pixelstypically include subpixels of various colors such as red, green, andblue.

SUMMARY OF PARTICULAR EMBODIMENTS

In one embodiment, a system includes a substrate, a plurality ofhexagon-shaped pixels coupled to the substrate, and a plurality ofconnector columns that electrically couple subpixels to the substrate.Each hexagon-shaped pixel includes a first subpixel formed on thesubstrate, a second subpixel stacked on top of the first subpixel, and athird subpixel stacked on top of the second subpixel. Each of the first,second, and third subpixels include a photodetector layer locatedbetween a transparent cathode layer and a transparent anode layer. Eachtransparent cathode layer and transparent anode layer of each subpixelis electrically coupled to the substrate through a respective one of theplurality of connector columns.

In another embodiment, a pixel for an image sensor includes a firstsubpixel and a second subpixel stacked on top of the first subpixel.Each of the first and second subpixels include a polygon shape. Each ofthe first and second subpixels include a photodetector layer, atransparent cathode layer, and a transparent anode layer.

In another embodiment, a method of manufacturing a pixel for an imagesensor includes creating a first subpixel by performing at least foursteps. The first step includes creating a transparent insulating layerby depositing a layer of transparent insulating material and thenpatterning the layer of transparent insulating material usinglithography. The second step includes creating a transparent cathodelayer of a subpixel by depositing a layer of transparent conductivematerial on the patterned transparent insulating layer and thenpatterning the transparent cathode layer using lithography, whereinpatterning the transparent cathode layer comprises forming a portion ofthe transparent cathode layer into a polygon shape. The third stepincludes creating a photodetector layer of the subpixel by depositing alayer of photodetecting material on the patterned transparent cathodelayer and then patterning the photodetector layer using lithography,wherein patterning the photodetector layer comprises forming a portionof the photodetector layer into the polygon shape. The fourth stepincludes creating a transparent anode layer of the subpixel bydepositing a layer of transparent anode material on the patternedphotodetector layer and then patterning the transparent anode layerusing lithography, wherein patterning the transparent anode layercomprises forming a portion of the transparent anode layer into thepolygon shape. The method further includes creating a second subpixel ontop of the first subpixel by repeating the first, second, third, andfourth steps.

The present disclosure presents several technical advantages. In someembodiments, three subpixels (e.g., red, green, and blue) are verticallystacked on top of one another to create either display or sensor pixels.By vertically stacking the RGB subpixel components, certain embodimentsremove the need for color filters and polarizers which are typicallyrequired in pixel technologies such as liquid crystal displays (LCD) andorganic light-emitting diode (OLED). This results in smaller pixel areasand greater pixel densities for higher resolutions than typicaldisplays. Some embodiments utilize electroluminescent quantum dottechnology that provides more efficient use of power and significantlyhigher contrast ratios than technologies such as LCD can offer.Additionally, because each subpixel may be controlled directly byvoltage, faster response times are possible than with technologies suchas LCD. Embodiments that utilize quantum dots that are finely tuned toemit a very narrow band of color provide purer hues and improved colorgamut over existing technologies such as OLED and LCD. Thin film designof certain embodiments results in substantial weight and bulk reduction.These and other advantages result in a low-cost, power efficientelectronic display/sensor solution capable of high dynamic range outputwith a small enough pixel pitch to meet the needs of extremelyhigh-resolution applications.

Other technical advantages will be readily apparent to one skilled inthe art from FIGS. 1 through 21, their descriptions, and the claims.Moreover, while specific advantages have been enumerated above, variousembodiments may include all, some, or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a single display pixel with vertically stackedsubpixels, according to certain embodiments;

FIGS. 2-3 illustrate exploded views of the display pixel of FIG. 1,according to certain embodiments;

FIG. 4 illustrates an array of pixels with stacked subpixels, accordingto certain embodiments;

FIG. 5 is a method of manufacturing a display pixel with stackedsubpixels, according to certain embodiments;

FIG. 6A illustrates a first insulating layer of the pixel of FIG. 1,according to certain embodiments;

FIG. 6B illustrates a portion of a photomask used to manufacture thefirst insulating layer of FIG. 6A, according to certain embodiments;

FIG. 7A illustrates a cathode layer of the first subpixel of FIG. 1,according to certain embodiments;

FIG. 7B illustrates a portion of a photomask used to manufacture thecathode layer of FIG. 7A, according to certain embodiments;

FIG. 8A illustrates an emissive layer of the first subpixel of FIG. 1,according to certain embodiments;

FIG. 8B illustrates a portion of a photomask used to manufacture theemissive layer of FIG. 8A, according to certain embodiments;

FIG. 9A illustrates an anode layer of the first subpixel of FIG. 1,according to certain embodiments;

FIG. 9B illustrates a portion of a photomask used to manufacture theanode layer of FIG. 9A, according to certain embodiments;

FIG. 10A illustrates a second insulating layer of the pixel of FIG. 1,according to certain embodiments;

FIG. 10B illustrates a portion of a photomask used to manufacture thesecond insulating layer of FIG. 10A, according to certain embodiments;

FIG. 11A illustrates a cathode layer of the second subpixel of FIG. 1,according to certain embodiments;

FIG. 11B illustrates a portion of a photomask used to manufacture thecathode layer of FIG. 11A, according to certain embodiments;

FIG. 12A illustrates an emissive layer of the second subpixel of FIG. 1,according to certain embodiments;

FIG. 12B illustrates a portion of a photomask used to manufacture theemissive layer of FIG. 12A, according to certain embodiments;

FIG. 13A illustrates an anode layer of the second subpixel of FIG. 1,according to certain embodiments;

FIG. 13B illustrates a portion of a photomask used to manufacture theanode layer of FIG. 13A, according to certain embodiments;

FIG. 14A illustrates a third insulating layer of the pixel of FIG. 1,according to certain embodiments;

FIG. 14B illustrates a portion of a photomask used to manufacture thethird insulating layer of FIG. 1.4A, according to certain embodiments;

FIG. 15A illustrates a cathode layer of the third subpixel of FIG. 1,according to certain embodiments;

FIG. 15B illustrates a portion of a photomask used to manufacture thecathode layer of FIG. 15A, according to certain embodiments;

FIG. 16A illustrates an emissive layer of the third subpixel of FIG. 1,according to certain embodiments;

FIG. 16B illustrates a portion of a photomask used to manufacture theemissive layer of FIG. 16A, according to certain embodiments;

FIG. 17A illustrates an anode layer of the third subpixel of FIG. 1,according to certain embodiments;

FIG. 17B illustrates a portion of a photomask used to manufacture theanode layer of FIG. 17A, according to certain embodiments;

FIG. 18 illustrates a single sensor pixel with vertically stackedsubpixels, according to certain embodiments;

FIGS. 19-20 illustrate exploded views of the sensor pixel of FIG. 18,according to certain embodiments; and

FIG. 21 is a method of manufacturing a sensor pixel with stackedsubpixels, according to certain embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Pixels are utilized in a variety of electronic displays and sensors. Forexample, displays used in smartphones, laptop computers, and televisionsutilize arrays of pixels to display images. As another example, sensorsused in cameras utilize arrays of pixels to capture images. Pixels mayin some instances include subpixels of various colors. For example, somepixels may include red, blue, and green subpixels. Subpixels aretypically co-planar and adjacent to each other within a pixel. Havingco-planar subpixels may be problematic in some applications, however,due to physical size requirements. For example, some electronic displaysrequire an extremely small pixel pitch (i.e., the distance between eachpixel) to provide enough resolution for visual acuity. Doing so with ahigh dynamic range is problematic given the lower light output due tophysical size reduction of the pixels themselves and the circuitrynormally surrounding them.

To address these and other problems with existing pixel designs,embodiments of the disclosure provide pixels with vertically stackedsubpixels that reduces the physical space required for each pixel. Forexample, some embodiments include three transparent overlapping red,green, and blue subpixels that are vertically stacked on top of oneanother. By vertically stacking the subpixels instead of locating themwithin the same plane, a higher number of pixels can be fit into adisplay or sensor area, thus providing the high pixel densities requiredby certain applications.

In embodiments that emit light (e.g., pixels for electronic displays),light emitted from the vertically stacked subpixels is additivelycombined to create the full color representation. This is in contrast toexisting technologies that utilize subtraction with filters andpolarization to create various colors of light. In some embodiments,each individual subpixel structure includes a transparent front emissiveplane and a transparent back circuitry plane. The front plane mayinclude transparent conductive film electrodes, charge injection layers,and a tuned color-specific electroluminescent quantum dot layer. Drivingcircuitry for each subpixel is accomplished by a back plane of layeredtransparent transistor/capacitor arrays to handle voltage switching andstorage for each subpixel. Example embodiments of display pixels areillustrated in FIGS. 1-3, and a method of manufacturing display pixelsis illustrated in FIG. 5.

In embodiments that sense light (e.g., pixels for sensor arrays), lightentering the vertically stacked subpixels passes through to subsequentlayers, with narrow bands of light captured by each subpixel layer foraccurate color imaging. In some embodiments, each individual subpixelstructure is an assembly of transparent layers of tuned color-specificphotoelectric quantum dot films, conductive films, and semiconductorfilms that are patterned to create a phototransistor array. Readout fromthis array carries voltage from specific pixels only in response to theamount of color present in the light entering a given subpixel layer.Since each layer is tuned to detect only a particular band of light,photoelectric voltage is produced according to the percentage of thatband contained within the wavelength of the incoming light. Exampleembodiments of sensor pixels are illustrated in FIGS. 18-20, and amethod of manufacturing sensor pixels is illustrated in FIG. 21.

To facilitate a better understanding of the present disclosure, thefollowing examples of certain embodiments are given. The followingexamples are not to be read to limit or define the scope of thedisclosure. Embodiments of the present disclosure and its advantages arebest understood by referring to FIGS. 1-21, where like numbers are usedto indicate like and corresponding parts.

FIGS. 1-4 illustrate various views of a single display pixel 100 withvertically stacked subpixels 110. FIG. 1 illustrates an assembled pixel100, FIGS. 2-3 illustrate different exploded views of pixel 100, andFIG. 4 illustrates an array of pixels 100. In general, these figuresdepict the conductive portions of the illustrated layers. Otherinsulating areas (e.g., outside and between the subpixel stacks) havebeen removed for sake of visual clarity.

Display pixel 100 may be utilized in any electronic display such as adisplay of a smartphone, laptop computer, television, a near-eye display(e.g., a head-mounted display), a heads-up display (HUD), and the like.In general, pixel 100 includes multiple subpixels 110 that arevertically stacked on one another. For example, some embodiments ofpixel 100 may include three subpixels 110: first subpixel 110A formed ona substrate (e.g., backplane driving circuitry), second subpixel 110Bthat is stacked on top of first subpixel 110A, and third subpixel 110Cthat is stacked on top of second subpixel 110B. In a particularembodiment, first subpixel 110A is a red subpixel (i.e., first subpixel110A emits red light), second subpixel 110B is a green subpixel (i.e.,second subpixel 110B emits green light), and third subpixel 110C is ablue subpixel (i.e., third subpixel 110C emits blue light). However,other embodiments may include any other order of red, green, and bluesubpixels 110 (e.g., RBG, GRB, GBR, BRG, or BGR). Furthermore, someembodiments may include more or few numbers of subpixels 110 than whatis illustrated in FIGS. 1-4 and may include any other appropriate colorsof subpixels (e.g., yellow, amber, violet, etc.) or non-visiblewavelengths.

In some embodiments, pixel 100 is coupled to backplane circuitry 120which may be formed on a substrate or backplane. In some embodiments,circuitry 120 includes layered transparent transistor/capacitor arraysto handle voltage switching and storage for each subpixel 110. Variouslayers of each subpixel 110 (e.g., anode layers 220 and cathode layers230 as described below) may be electrically coupled to circuitry 120 viaconnector columns 130 and connection pads 140. For example, firstsubpixel 110A may be coupled to circuitry 120 via connector columns 130Aand 130B and connection pads 140A and 140B, second subpixel 110B may becoupled to circuitry 120 via connector columns 130C and 130D andconnection pads 140C and 140D, and third subpixel 110C may be coupled tocircuitry 120 via connector columns 130E and 130F and connection pads140E and 140F, as illustrated. As a result, each subpixel 110 may beindividually addressed and controlled by circuitry 120.

As illustrated in detail in FIGS. 2-3, each subpixel 110 may include atleast three layers: an emissive layer 210, an anode layer 220, and acathode layer 230. For example, subpixel 110A may include at least acathode layer 230A, an emissive layer 210A on top of cathode layer 230A,and an anode layer 220A on top of emissive layer 210A. Likewise,subpixel 110B may include at least a cathode layer 230B, an emissivelayer 210B on top of cathode layer 230B, and an anode layer 220B on topof emissive layer 210B. Similarly, subpixel 110C may include at least acathode layer 230C, an emissive layer 210C on top of cathode layer 230C,and an anode layer 220C on top of emissive layer 210C. In otherembodiments, subpixels 110 may include additional layers that are notillustrated in FIGS. 2-3. For example, some embodiments of subpixels 110may include additional insulating layers 310 that are not specificallyillustrated. As a specific example, some embodiments of emissive layers210 may include multiple sub-layers of OLED emission architectures orelectroluminescent quantum dot architectures.

Anode layers 220 and cathode layers 230 are formed, respectively, fromany appropriate anode or cathode material. For example, anode layers 220and cathode layers 230 may include simple conductive polymers (orsimilar materials) used as transparent electrodes. In general, anodelayers 220 and cathode layers 230 are transparent so that light may passfrom emissive layers 210 and combine with light from subsequentsubpixels 110.

Emissive layers 210 generally are formed from any appropriate materialcapable of emitting light while supporting transparency. In someembodiments, emissive layers 210 may include both electroluminescentcapabilities (e.g., a diode converting electric current into light) andphotoluminescent capabilities (for down-converting incominghigher-energy light to lower-energy wavelengths). For example, emissivelayers 210 may be tuned color-specific electroluminescent quantum dot(QD) layers such as quantum-dot-based light-emitting diode (QLED)layers. In some embodiments, emissive layers 210 may be organiclight-emitting diode (OLED) layers. In general, emissive layers 210 maybe precisely tuned for narrow band emission of specific wavelengths oflight (e.g., red, green, and blue). By using electroluminescent QDemissive layers 210, certain embodiments provide 1) more efficient useof power than other methods such as liquid crystal displays (LCD), and2) significantly higher contrast ratios than other technologies such asLCD can offer. And because each subpixel 110 is controlled directly byvoltage, faster response times are possible than with technologies suchas LCD. Furthermore, implementing quantum dots which are finely tuned toemit a very narrow band of color provides purer hues and improved colorgamut over both OLED and LCD technologies.

In some embodiments, pixels 100 and subpixels 110 have an overall shapeof a polygon when viewed from above. For example, pixels 100 andsubpixels 110 may be hexagon-shaped, octagon-shaped, or the shape of anyother polygon such as a triangle or quadrangle. To achieve the desiredshape, each layer of subpixel 110 may be formed in the desired shape.For example, each of anode layer 220, emissive layer 210, and cathodelayer 230 may be formed in the shape of the desired polygon. As aresult, each side of pixel 100 may be adjacent to a side of anotherpixel 100 as illustrated in FIG. 4. For example, if pixel 100 is in theshape of a hexagon, each pixel 100 in an array of pixels such as array400 is adjacent to six other pixels 100. Furthermore, each side of eachindividual pixel 100 is adjacent to a side of a respective one of thesix other hexagon-shaped pixels 100. In this way, the emissive area ofthe overall display surface is maximized since only very narrownon-conductive boundaries are patterned between each pixel. Thisdiminishes the percentage of non-emissive “dark” areas within array 400.

Embodiments of pixels 100 include multiple connector columns 130 thatelectrically connect the various layers of subpixels 110 to circuitry120 via connection pads 140. For example, in some embodiments, pixel 100includes six connector columns 130: connector column 130A that couplescathode layer 230A of subpixel 110A to circuitry 120, connector column130B that couples anode layer 220A of subpixel 110A to circuitry 120,connector column 130C that couples cathode layer 230B of subpixel 110Bto circuitry 120, connector column 130D that couples anode layer 220B ofsubpixel 110B to circuitry 120, connector column 130E that couplescathode layer 230C of subpixel 110C to circuitry 120, and connectorcolumn 130F that couples anode layer 220C of subpixel 110C to circuitry120.

In general, connector columns 130 are connected only to a single layerof pixel 100 (i.e., a single anode layer 220 or cathode layer 230),thereby permitting circuitry 120 to uniquely address each anode layer220 and cathode layer 230 of pixel 100. For example, connector column130F is coupled only to anode layer 220C of subpixel 110C, asillustrated. Connector columns 130 are built up with one or moreconnector column portions 135, as illustrated in FIGS. 6A-16B. Eachconnector column portion 135 is an island of material that iselectrically isolated from the layer on which it is formed, but permitsan electrical connection between the various layers of connector column130. Connector columns 130 are generally adjacent to a single side ofpixel 100 and occupy less than half of the length of a single side ofpixel 100 in order to allow enough space for a connector column 130 ofan adjacent pixel 100. For example, as illustrated in FIG. 4, connectorcolumn 130E of pixel 100A occupies one side of pixel 100 but leavesenough space for connector column 130B of pixel 100B. In addition, theconnector columns 130 of a particular pixel 100 all have unique heights,in some embodiments. In the illustrated embodiment, for example,connector column 130F is the full height of pixel 100, while connectorcolumn 130B is only as tall as subpixel 110A. That is, the height of aparticular connector column 130 may depend on the path of the particularconnector column 130 to its connection pad 140. Connector columns 130may be any appropriate size or shape. For example, connector columns 130may be in the shape of a square, rectangle, circle, triangle, trapezoid,or any other appropriate shape.

Embodiments of pixel 100 may have one or more insulating layers 310, asillustrated in FIGS. 2-3. For example, some embodiments of pixel. 100may include a first insulating layer 310A between cathode layer 230A ofsubpixel. 110A and circuitry 120, a second insulating layer 310B betweencathode layer 230B of subpixel 110B and anode layer 220A of subpixel.110A, and a third insulating layer 310C between cathode layer 230C ofsubpixel 110C and anode layer 220B of subpixel 110B. Insulating layers310 may be any appropriate material that electrically isolates adjacentlayers of pixel 100.

FIG. 5 illustrates a method 500 of manufacturing a display pixel withstacked subpixels. For example, method 500 may be used to manufacturepixel 100 having stacked subpixels 110, as described above. Method 500,in general, utilizes steps 510-540 to create layers of a subpixel usinglithography. The various layers created by these steps and thephotomasks that may be utilized to create the various layers areillustrated in FIGS. 6A-17B, wherein the insulating material has beenremoved from the layers to allow a better view of the structure ofconductive elements. As described in more detail below, steps 510-540may be repeated one or more times to create stacked subpixels such assubpixels 110 of pixel 100. For example, steps 510-540 may be performeda total of three times to create stacked subpixels 110A-110C, asdescribed above.

Method 500 may begin in step 510 where a transparent insulating layer iscreated by depositing a layer of transparent insulating material andthen patterning the layer of transparent insulating material usinglithography. In some embodiments, the transparent insulating layer isinsulating layer 310A, which is illustrated in FIG. 6A. In someembodiments, the layer of transparent insulating material is depositedon a substrate or backplane that includes circuitry 120, as describedabove. In some embodiments, the layer of transparent insulating materialis patterned into the transparent insulating layer usingphotolithography. A portion of a photomask 600 that may be utilized bythis step to pattern the layer of transparent insulating material intothe transparent insulating layer is illustrated in FIG. 6B.

At step 520, a transparent cathode layer of a subpixel is created bydepositing a layer of transparent conductive material on the patternedtransparent insulating layer of step 510 and then patterning thetransparent cathode layer using lithography such as photolithography. Insome embodiments, the transparent cathode layer is cathode layer 230A,which is illustrated in FIG. 7A. A portion of a photomask 700 that maybe utilized by this step to pattern the layer of transparent conductivematerial into the transparent cathode layer is illustrated in FIG. 7B.In some embodiments, patterning the transparent cathode layer includesforming a portion of the transparent cathode layer into a polygon shape,such as a hexagon or an octagon. For example, as illustrated in FIG. 7B,the transparent cathode layer of a single subpixel may have an overallshape of a hexagon when viewed from above and may include a portion of aconnector column 130 (e.g., in the shape of a rectangle or a square)coupled to one side of the hexagon shape.

At step 530, an emissive layer of a subpixel is created by depositing alayer of emissive material on the patterned transparent cathode layer ofstep 520 and then patterning the emissive layer using lithography suchas photolithography. In some embodiments, the emissive layer is emissivelayer 210A, which is illustrated in FIG. 8A. A portion of a photomask800 that may be utilized by this step to pattern the layer of emissivematerial into the emissive layer is illustrated in FIG. 8B. In someembodiments, patterning the emissive layer includes forming a portion ofthe emissive layer into a polygon shape, such as a hexagon or anoctagon. For example, as illustrated in FIG. 8B, the emissive layer of asingle subpixel may have an overall shape of a hexagon when viewed fromabove. Unlike the transparent cathode layer of step 520, the sides ofthe hexagon shape of the emissive layer of this step may be devoid ofany portions of connector columns 130.

In some embodiments, the color output of the emissive layers of step 530are precisely tuned for narrow band emission, resulting in extremelyaccurate color representation. In some embodiments, high contrast ratiosare achievable due to the lack of additional polarizers or filteringnecessary to govern the light output of each subpixel. This results inhigh dynamic range image reproduction with minimal required drivingvoltage.

At step 540, a transparent anode layer of a subpixel is created bydepositing a layer of transparent anode material on the patternedemissive layer of step 530 and then patterning the transparent anodelayer using lithography such as photolithography. In some embodiments,the transparent anode layer is anode layer 220A, which is illustrated inFIG. 9A. A portion of a photomask 900 that may be utilized by this stepto pattern the layer of transparent anode material into the transparentanode layer is illustrated in FIG. 9B. In some embodiments, patterningthe transparent anode layer includes forming a portion of thetransparent anode layer into a polygon shape, such as a hexagon or anoctagon. For example, as illustrated in FIG. 9B, the transparent anodelayer of a single subpixel may have an overall shape of a hexagon whenviewed from above and may include a portion of a connector column 130(e.g., in the shape of a rectangle or a square) coupled to one side ofthe hexagon shape.

At step 550, method 500 determines whether to repeat steps 510-540 basedon whether additional subpixels are to be formed. Using the exampleembodiment of FIG. 1, for example, method 500 would repeat steps 510-540two additional times in order to create second subpixel 110B on top offirst subpixel 110A and then third subpixel 110C on top of secondsubpixel 110B. To create second subpixel 110B on top of first subpixel110A, method 500 would repeat steps 510-540 to create the various layersillustrated in FIGS. 10A, 11A, 12A, and, 13A, respectively. Portions ofphotomasks 1000, 1100, 1200, and 1300 that may be utilized by thesesteps to create second subpixel 110B are illustrated in FIGS. 10B, 11B,12B, and, 13B, respectively. To create third subpixel 110C on top ofsecond subpixel 110B, method 500 would repeat steps 510-540 to createthe various layers illustrated in FIGS. 14A, 15A, 16A, and, 17A,respectively. Portions of photomasks 1400, 1500, 1600, and 1700 that maybe utilized by these steps to create third subpixel 110C are illustratedin FIGS. 14B, 15B, 16B, and, 17B, respectively.

In some embodiments, method 500 may include forming additional layersthat are not specifically illustrated in FIG. 5. For example, additionallayers such as insulating layers 310 may be formed by method 500 at anyappropriate location. As another example, some embodiments may includeone or more additional layers of graphene or other similarelectrically-enhancing materials in order to improve efficiency andconductivity.

As described above, pixels with vertically stacked subpixels may beutilized as either display or sensor pixels. The previous figuresillustrated embodiments of display pixels 100 that include emissivelayers 210. The following FIGS. 18-20, however, illustrate embodimentsof sensor pixels 1800 with vertically stacked subpixels 110 that includephotodetector layers 1910 in place of emissive layers 210. FIG. 18illustrates an assembled sensor pixel 1300 and FIGS. 19-20 illustratedifferent exploded views of sensor pixel 1800. In general, these figuresdepict the conductive port ions of the illustrated layers. Otherinsulating areas (e.g., outside and between the subpixel stacks) havebeen removed for sake of visual clarity.

Sensor pixel 1800 may be utilized in any electronic devices such ascameras that are used to sense or capture light (e.g., photos andvideos). Like display pixel 100, sensor pixel 1800 includes multiplesubpixels 110 that are vertically stacked on top of one another. Forexample, some embodiments of pixel 1800 may include three subpixels 110:first subpixel 110A, second subpixel 110B that is stacked on top offirst subpixel 110A, and third subpixel 110C that is stacked on top ofsecond subpixel 110B. In a particular embodiment, first subpixel 110A isa red subpixel (i.e., first subpixel 110A detects red light), secondsubpixel 110B is a green subpixel (i.e., second subpixel 110B detectsgreen light), and third subpixel 110C is a blue subpixel (i.e., thirdsubpixel 110C detects blue light). However, other embodiments mayinclude any other order of red, green, and blue subpixels 110.Furthermore, some embodiments may include more or few numbers ofsubpixels 110 than what is illustrated in FIGS. 18-20 and may includeany other appropriate colors of subpixels (e.g., violet, etc.).

Like display pixel 100, sensor pixel 1800 may be coupled to backplanecircuitry 120. In some embodiments, circuitry 120 includes layeredtransparent transistor/capacitor arrays to handle voltage switching andstorage for each subpixel 110 of pixel 1800. Various layers of eachsubpixel 110 (e.g., anode layers 220 and cathode layers 230 as describedabove) may be electrically coupled to circuitry 120 via connectorcolumns 130 and connection pads 140. For example, first subpixel 110Amay be coupled to circuitry 120 via connector columns 130A and 130B andconnection pads 140A and 140B, second subpixel. 110B may be coupled tocircuitry 120 via connector columns 130C and 130D and connection pads140C and 140D, and third subpixel 110C may be coupled to circuitry 120via connector columns 130E and 130F and connection pads 140E and 140F,as illustrated. As a result, each subpixel 110 may be individuallyaddressed and controlled by circuitry 120.

As illustrated in detail in FIGS. 19-20, each subpixel 110 of sensorpixel 1800 may include at least three layers: a photodetector layer1910, an anode layer 220, and a cathode layer 230. For example, subpixel110A may include at least a cathode layer 230A, a photodetector layer1910A on top of cathode layer 230A, and an anode layer 220A on top ofphotodetector layer 1910A. Likewise, subpixel 110B may include at leasta cathode layer 230B, a photodetector layer 1910B on top of cathodelayer 230B, and an anode layer 220B on top of photodetector layer 1910B.Similarly, subpixel 110C may include at least a cathode layer 2300, aphotodetector layer 1910C on top of cathode layer 230C, and an anodelayer 220C on top of photodetector layer 1910C. In other embodiments,subpixels 110 may include additional layers that are not illustrated inFIGS. 18-20. For example, some embodiments of subpixels 110 may includeadditional insulating layers 310 that are not specifically illustrated.As another example, some embodiments may include one or more additionallayers of graphene or other similar electrically-enhancing materials inorder to improve efficiency and conductivity.

As discussed above with respect to FIGS. 2-3, anode layers 220 andcathode layers 230 are formed, respectively, from any appropriate anodeor cathode material. In general, anode layers 220 and cathode layers 230are transparent so that light may pass through them and intophotodetector layers 1910. Only narrow bands of light are captured byeach photodetector layer 1910 for accurate color imaging.

Photodetector layers 1910 generally are formed from any appropriatematerial capable of detecting light while supporting transparency. Forexample, photodetector layers 1910 may be tuned color-specificelectroluminescent QD layers such as QLED layers. In some embodiments,photodetector layers 1910 may be OLED layers. In some embodiments,photodetector layers 1910 may be precisely tuned for narrow banddetection of specific wavelengths of light (e.g., red, green, and blue).By using electroluminescent QD photodetector layers 1910, certainembodiments provide 1) improved color gamut in the resulting imagerysince precisely-tuned photoelectric quantum dot films are used tocapture only the band of light necessary for a given subpixel, and 2)greatly improved shutter speeds over traditional CMOS image sensors dueto very fast response times of quantum dot photoelectric materials.

In some embodiments, photodetector layers 1910 utilize any transparentphotodetector material in combination with unique color filteringinstead of QD photodetectors. For example, as depicted in FIG. 19, fullspectrum light may first enter sensor pixel 1800 from the top (i.e.,through third subpixel 110C). Third subpixel 110C may include a specificcolor filter as an additional “sub-layer” (e.g., within photodetectorlayer 1910) to allow only certain wavelengths of light to pass through.Second subpixel 110B may include a color filter of a different specificcolor to allow only other certain wavelengths of light to pass throughto first subpixel 110A beneath it. By mathematically subtracting thereadout signals from each of these subpixels 110, sensor pixel 1800 maybe able to isolate specific colors from the upper two subpixels (e.g.,110C and 110B), thus outputting a full RGB signal.

In some embodiments, sensor pixels 1800 and subpixels 110 have anoverall shape of a polygon when viewed from above. For example, pixels1800 and subpixels 110 may be hexagon-shaped, octagon-shaped, or theshape of any other polygon. To achieve the desired shape, each layer ofsubpixel 110 may be formed in the desired shape. For example, each ofanode layer 220, photodetector layer 1910, and cathode layer 230 may beformed in the shape of the desired polygon. As a result, each side ofpixel 1800 may be adjacent to a side of another pixel 1800, similar topixels 100 as illustrated in FIG. 4. For example, if pixel 1800 is inthe shape of a hexagon, each pixel 1800 in an array of pixels such asarray 400 is adjacent to six other pixels 1800. Furthermore, each sideof each individual pixel 1800 is adjacent to a side of a respective oneof the six other hexagon-shaped pixels 1800. In this way, the sensitivearea of the overall display surface is maximized since only very narrownon-conductive boundaries are patterned between each pixel. Thisdiminishes the percentage of non-emissive “dark” areas within an arrayof pixels 1800.

Like display pixels 100, embodiments of sensor pixels 1800 includemultiple connector columns 130 that electrically connect the variouslayers of subpixels 110 to circuitry 120 via connection pads 140. Forexample, in some embodiments, pixel 1800 includes six connector columns130: connector column 130A that couples cathode layer 230A of subpixel110A to circuitry 120, connector column 130B that couples anode layer220A of subpixel 110A to circuitry 120, connector column 130C thatcouples cathode layer 230B of subpixel 110B to circuitry 120, connectorcolumn 130D that couples anode layer 220B of subpixel 110B to circuitry120, connector column 130E that couples cathode layer 230C of subpixel110C to circuitry 120, and connector column 130F that couples anodelayer 220C of subpixel 110C to circuitry 120.

FIG. 21 illustrates a method 2100 of manufacturing a sensor pixel withstacked subpixels. For example, method 2100 may be used to manufacturepixel 1800 having stacked subpixels 110, as described above. Method2100, in general, utilizes steps 2110-2140 to create layers of asubpixel using lithography. The various layers created by these stepsand the photomasks that may be utilized to create the various layers areillustrated in FIGS. 6A-17B, except that emissive layers 210 arereplaced by photodetector layers 1910. As described in more detailbelow, steps 2110-2140 may be repeated one or more times to createstacked subpixels such as subpixels 110 of pixel 1800. For example,steps 2110-2140 may be performed a total of three times to createstacked subpixels 11A-110C, as described above.

Method 2100 may begin in step 2110 where a transparent insulating layeris created by depositing a layer of transparent insulating material andthen patterning the layer of transparent insulating material usinglithography. In some embodiments, the transparent insulating layer isinsulating layer 310A, which is illustrated in FIG. 6A. In someembodiments, the layer of transparent insulating material is depositedon a substrate or backplane that includes circuitry 120, as describedabove. In some embodiments, the layer of transparent insulating materialis patterned into the transparent insulating layer usingphotolithography. A portion of a photomask 600 that may be utilized bythis step to pattern the layer of transparent insulating material intothe transparent insulating layer is illustrated in FIG. 6B.

At step 2120, a transparent cathode layer of a subpixel is created bydepositing a layer of transparent conductive material on the patternedtransparent insulating layer of step 2110 and then patterning thetransparent cathode layer using lithography such as photolithography. Insome embodiments, the transparent cathode layer is cathode layer 230A,which is illustrated in FIG. 7A. A portion of a photomask 700 that maybe utilized by this step to pattern the layer of transparent conductivematerial into the transparent cathode layer is illustrated in FIG. 7B.In some embodiments, patterning the transparent cathode layer includesforming a portion of the transparent cathode layer into a polygon shape,such as a hexagon or an octagon. For example, as illustrated in FIG. 7B,the transparent cathode layer of a single subpixel may have an overallshape of a hexagon when viewed from above and may include a portion of aconnector column 130 (e.g., in the shape of a rectangle or a square)coupled to one side of the hexagon shape.

At step 2130, a photodetector layer of a subpixel is created bydepositing a layer of photodetector material on the patternedtransparent cathode layer of step 2120 and then patterning thephotodetector layer using lithography such as photolithography. In someembodiments, the photodetector layer is photodetector layer 1910A, whichis illustrated in FIG. 8A (except that emissive layer 210A is replacedby photodetector layer 1910A). A portion of a photomask 800 that may beutilized by this step to pattern the layer of photodetector materialinto the photodetector layer is illustrated in FIG. 8B. In someembodiments, patterning the photodetector layer includes forming aportion of the photodetector layer into a polygon shape, such as ahexagon or an octagon. For example, as illustrated in FIG. 8B, thephotodetector layer of a single subpixel may have an overall shape of ahexagon when viewed from above. Unlike the transparent cathode layer ofstep 2120, the sides of the hexagon shape of the photodetector layer ofthis step may be devoid of any portions of connector columns 130.

At step 2140, a transparent anode layer of a subpixel is created bydepositing a layer of transparent anode material on the patternedphotodetector layer of step 2130 and then patterning the transparentanode layer using lithography such as photolithography. In someembodiments, the transparent anode layer is anode layer 220A, which isillustrated in FIG. 9A. A portion of a photomask 900 that may beutilized by this step to pattern the layer of transparent anode materialinto the transparent anode layer is illustrated in FIG. 9B. In someembodiments, patterning the transparent anode layer includes forming aportion of the transparent anode layer into a polygon shape, such as ahexagon or an octagon. For example, as illustrated in FIG. 9B, thetransparent anode layer of a single subpixel may have an overall shapeof a hexagon when viewed from above and may include a portion of aconnector column 130 (e.g., in the shape of a rectangle or a square)coupled to one side of the hexagon shape.

At step 2150, method 2100 determines whether to repeat steps 2110-2140based on whether additional subpixels are to be formed for pixel 1800.Using the example embodiment of FIG. 18, for example, method 2100 wouldrepeat steps 2110-2140 two additional times in order to create secondsubpixel 110B on top of first subpixel 110A and then third subpixel 110Con top of second subpixel 110B. To create second subpixel 110B on top offirst subpixel 110A, method 2100 would repeat steps 2110-2140 to createthe various layers illustrated in FIGS. 10A, 11A, 12A, and, 13A,respectively. Portions of photomasks 1000, 1100, 1200, and 1300 that maybe utilized by these steps to create second subpixel 110B areillustrated in FIGS. 10B, 11B, 12B, and, 13B, respectively. To createthird subpixel 110C on top of second subpixel 110B, method 2100 wouldrepeat steps 2110-2140 to create the various layers illustrated in FIGS.14A, 121A, 16A, and, 17A, respectively. Portions of photomasks 1400,12100, 1600, and 1700 that may be utilized by these steps to createthird subpixel 110C are illustrated in FIGS. 14B, 121B, 16B, and, 17B,respectively.

In some embodiments, method 2100 may include forming additional layersthat are not specifically illustrated in FIG. 21. For example,additional layers such as insulating layers 310 may be formed by method2100 at any appropriate location. Furthermore, as previously noted, somesteps of some embodiments of method 210 may include additional stepsthat are not specifically mentioned. For example, some layers (e.g.,some insulating layers) may be a combination of both insulating andconductive films. Such layers may be manufactured using standard planarsemiconductor techniques: depositing, masking, etching, and repeating asmany times as necessary to produce the required pattern of conductiveand non-conductive areas within the layer.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

Herein, the phrase “on top” when used to describe subpixels 110 andtheir various layers (e.g., layers 210, 220, and 230) refers to aviewing direction for display pixels 100 and a light entry direction forsensor pixels 1800. As an example, subpixel 110B of display pixel 100 isdescribed as being stacked “on top” of subpixel 110A. As illustrated inFIGS. 2-3, “on top” means that subpixel 110B is on the side of subpixel110A that is towards the location that the combined light that isemitted from display pixel 100 may be viewed. Stated another way,subpixel 110B is on the opposite side of subpixel 100A from circuitry120. As another example, subpixel 110C of sensor pixel 1800 is describedas being stacked “on top” of subpixel 110B. As illustrated in FIGS.19-20, “on top” means that subpixel 110C is on the side of subpixel 110Bthat is towards the location that the full spectrum light enters sensorpixel 1800.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

Although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,functions, operations, or steps, any of these embodiments may includeany combination or permutation of any of the components, elements,functions, operations, or steps described or illustrated anywhere hereinthat a person having ordinary skill in the art would comprehend.

Furthermore, reference in the appended claims to an apparatus or systemor a component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A system comprising: a substrate; a plurality ofhexagon-shaped pixels coupled to the substrate, each hexagon-shapedpixel comprising: a first subpixel formed on the substrate; a secondsubpixel stacked on top of the first subpixel; and a third subpixelstacked on top of the second subpixel; and a plurality of connectorcolumns that electrically couple the first, second, and third subpixelsto the substrate; wherein: each of the first, second, and thirdsubpixels comprises a photodetector layer located between a transparentcathode layer and a transparent anode layer; and each transparentcathode layer and transparent anode layer of each subpixel iselectrically coupled to the substrate through a respective one of theplurality of connector columns.
 2. The system of claim 1, wherein eachconnector column of each particular hexagon-shaped pixel is adjacent toa respective side of the particular hexagon-shaped pixel.
 3. The systemof claim 1, wherein the plurality of hexagon-shaped pixels comprises afirst pixel that is adjacent to six other hexagon-shaped pixels, eachside of the first pixel being adjacent to a side of a respective one ofthe six other hexagon-shaped pixels.
 4. The system of claim 1, whereinthe plurality of connector columns are in the shape of a square, arectangle, a circle, a triangle, or a trapezoid.
 5. The system of claim1, wherein the plurality of connector columns comprise six connectorcolumns, wherein each of the six connector columns has a differentheight from the remaining connector columns of the six connectorcolumns.
 6. The system of claim 1, wherein each photodetector layercomprises: a quantum dot layer; an organic light-emitting diode (OLED)layer; a quantum-dot-based light-emitting diode (QLED) layer; or atransparent photodetector material and a color filter.
 7. The system ofclaim 1, wherein the photodetector layers of the first, second, andthird subpixels are configured to detect a respective color selectedfrom the group consisting of red, blue, and green.
 8. A pixel for animage sensor, the pixel comprising: a first subpixel; and a secondsubpixel stacked on top of the first subpixel; wherein: each of thefirst and second subpixels comprises a polygon shape; and each of thefirst and second subpixels comprises a photodetector layer, atransparent cathode layer, and a transparent anode layer.
 9. The pixelof claim 8, wherein the polygon shape comprises a hexagon, an octagon, atriangle, or a quadrangle.
 10. The pixel of claim 8, further comprisinga plurality of connector columns that electrically couple the first andsecond subpixels to a substrate, wherein each connector column isadjacent to a respective side of the polygon shape of the first andsecond subpixels.
 11. The pixel of claim 10, wherein the plurality ofconnector columns are in the shape of a square, a rectangle, or acircle.
 12. The pixel of claim 10, wherein the plurality of connectorcolumns comprise four connector columns and the polygon shape comprisesa hexagon, wherein each of the four connector columns has a differentheight from the remaining connector columns of the four connectorcolumns.
 13. The pixel of claim 8, wherein each photodetector layercomprises: a quantum dot layer; an organic light-emitting diode (OLED)layer; a quantum-dot-based light-emitting diode (QLED) layer; or atransparent photodetector material and a color filter.
 14. The pixel ofclaim 8, wherein: the photodetector layer of each particular subpixel ison top of the transparent cathode layer of the particular subpixel; andthe transparent anode layer of each particular subpixel is on top of thephotodetector layer of the particular subpixel.
 15. The pixel of claim8, wherein the pixel is devoid of any polarizing and filtering layers.16. A method of manufacturing a pixel for an image sensor, the methodcomprising: creating a first subpixel by: performing a first step ofcreating a transparent insulating layer by depositing a layer oftransparent insulating material and then patterning the layer oftransparent insulating material using lithography; performing a secondstep of creating a transparent cathode layer of a subpixel by depositinga layer of transparent conductive material on the patterned transparentinsulating layer and then patterning the transparent cathode layer usinglithography, wherein patterning the transparent cathode layer comprisesforming a portion of the transparent cathode layer into a polygon shape;performing a third step of creating a photodetector layer of thesubpixel by depositing a layer of photodetecting material on thepatterned transparent cathode layer and then patterning thephotodetector layer using lithography, wherein patterning thephotodetector layer comprises forming a portion of the photodetectorlayer into the polygon shape; and performing a fourth step of creating atransparent anode layer of the subpixel by depositing a layer oftransparent anode material on the patterned photodetector layer and thenpatterning the transparent anode layer using lithography, whereinpatterning the transparent anode layer comprises forming a portion ofthe transparent anode layer into the polygon shape; and creating asecond subpixel on top of the first subpixel by repeating the first,second, third, and fourth steps.
 17. The method of manufacturing thepixel for the image sensor of claim 16, wherein the lithographycomprises photolithography.
 18. The method of manufacturing the pixelfor the image sensor of claim 16, wherein the polygon shape comprises ahexagon, an octagon, a triangle, or a quadrangle.
 19. The method ofmanufacturing the pixel for the image sensor of claim 16, wherein thephotodetecting material of the third step comprises: a quantum dotmaterial; an organic light-emitting diode (OLED) material; aquantum-dot-based light-emitting diode (QLED) material; or a transparentphotodetector material and a color filter.
 20. The method ofmanufacturing the pixel for the image sensor of claim 16, wherein:patterning the transparent cathode layer of the second step furthercomprises forming a portion of a first connection column on at least oneside of the polygon shape of the transparent cathode layer; andpatterning the transparent anode layer of the fourth step furthercomprises forming a portion of a second connection column on at leastone side of the polygon shape of the transparent anode layer.